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#1
A64 / Re: PE16/POWERON PIN with 1k r...
Last post by LubOlimex - Today at 09:47:35 AMNo idea, it should be explained in AXP803 datasheet.
Did you keep the PWRON to GND all the time? If you release the GND connection the AXP803 is supposed to boot.
Did you keep the PWRON to GND all the time? If you release the GND connection the AXP803 is supposed to boot.
#2
A64 / PE16/POWERON PIN with 1k resis...
Last post by mauricio - November 05, 2025, 04:13:22 PMHello.
After discovering the PE16 pin 37 at GPIO has R65, but no R28, I solder one there
Now when connect GND to pin 37, A64 poweroff, but reboot. I would like it remain off
Is there's something else to do to achieve a poweroff with PE16 ?
Thanks
After discovering the PE16 pin 37 at GPIO has R65, but no R28, I solder one there
Now when connect GND to pin 37, A64 poweroff, but reboot. I would like it remain off
Is there's something else to do to achieve a poweroff with PE16 ?
Thanks
#3
UEXT / Re: ESP32-PoE-ISO-16MB --> MOD...
Last post by LubOlimex - November 05, 2025, 11:19:31 AMIt is clear then. In your case MOD-BME280 won't get powered properly. Basically the 3.3V output from MOD-IO is disconnected. In the way you use it, MOD-BME280 gets parasitically powered via the I2C lines. This is side effect and a problem, it is not a feature or a recommended way to use the boards together.
In order to enable the 3.3V output at the UEXT_FEMALE header, you need to solder R16 on MOD-IO board. It is located just under the UEXT_FEMALE connector on the top of the board.
We've disabled this 3.3V line by default to avoid short-circuits when multiple MOD-IO boards are connected (and each powered from own power supply). But in your case you need to simply solder 0R resistor size 0603 on R16 pads and things will start working properly.
Again refer to the schematic to understand better:
https://www.olimex.com/Products/Modules/IO/MOD-IO/resources/MOD-IO-schematic.pdf
The alternative is to connect MOD-IO and MOD-BME280 in parallel (e.g. not MOD-BME280 after the MOD-IO). This way MOD-BME280 will get powered from ESP32-POE-ISO (where 3.3V output on the UEXT is enabled by default).
In order to enable the 3.3V output at the UEXT_FEMALE header, you need to solder R16 on MOD-IO board. It is located just under the UEXT_FEMALE connector on the top of the board.
We've disabled this 3.3V line by default to avoid short-circuits when multiple MOD-IO boards are connected (and each powered from own power supply). But in your case you need to simply solder 0R resistor size 0603 on R16 pads and things will start working properly.
Again refer to the schematic to understand better:
https://www.olimex.com/Products/Modules/IO/MOD-IO/resources/MOD-IO-schematic.pdf
The alternative is to connect MOD-IO and MOD-BME280 in parallel (e.g. not MOD-BME280 after the MOD-IO). This way MOD-BME280 will get powered from ESP32-POE-ISO (where 3.3V output on the UEXT is enabled by default).
#4
A64 / Re: TWI2 (i2c-2) external pull...
Last post by LubOlimex - November 05, 2025, 09:17:48 AMHello mauricio,
Please be more specific. What interface do you want to use exactly (e.g. SPI, TWI/I2C, UART, just GPIO, etc)? Where are you planning to connect your peripheral at the board exactly (e.g. GPIO header, UEXT, etc)?
Not all interfaces require adding anything. For example, if you use TWI1 at UEXT1 header there are already 2.2k pull up resistors placed.
Usually it is best idea first to check the schematic of your exact board revision here:
https://github.com/OLIMEX/OLINUXINO/tree/master/HARDWARE/A64-OLinuXino/2.%20Older%20hardware%20revisions
Please be more specific. What interface do you want to use exactly (e.g. SPI, TWI/I2C, UART, just GPIO, etc)? Where are you planning to connect your peripheral at the board exactly (e.g. GPIO header, UEXT, etc)?
Not all interfaces require adding anything. For example, if you use TWI1 at UEXT1 header there are already 2.2k pull up resistors placed.
Usually it is best idea first to check the schematic of your exact board revision here:
https://github.com/OLIMEX/OLINUXINO/tree/master/HARDWARE/A64-OLinuXino/2.%20Older%20hardware%20revisions
#5
UEXT / Re: ESP32-PoE-ISO-16MB --> MOD...
Last post by swaff - November 04, 2025, 08:17:45 PMThis is the Olimex MOD-BME280. It is connected directly to the MOD-IO via UEXT (no cable). The MOD-IO is connected via an included cable to the Olimex ESP32-PoE-ISO-16MB UEXT port.
The MOD-IO is powered via the jack. I've tried both USB and PoE power to power the ESP32 with no change.
The MOD-BME280 is powered via the UEXT connector as I thought that's how it was supposed to work. And most of the time it does work, but sometimes the humdity reading disappears, and even more rarely I've seen temperature and pressure stop working.
The MOD-IO is powered via the jack. I've tried both USB and PoE power to power the ESP32 with no change.
The MOD-BME280 is powered via the UEXT connector as I thought that's how it was supposed to work. And most of the time it does work, but sometimes the humdity reading disappears, and even more rarely I've seen temperature and pressure stop working.
#6
A64 / Re: TWI2 (i2c-2) external pull...
Last post by mauricio - November 04, 2025, 06:26:48 PMHello. I have an Olinuxino A64, rev. G.
Where in the pcb the resistors should be ?, or the pads ?.
I've looking for them for some time now, cant find.
Thanks
Where in the pcb the resistors should be ?, or the pads ?.
I've looking for them for some time now, cant find.
Thanks
#7
UEXT / Re: ESP32-PoE-ISO-16MB --> MOD...
Last post by LubOlimex - November 04, 2025, 08:28:30 AM1. How do you power the BME280? If you want to power it from the MOD-IO, it will not work since the 3.3V powering is disabled by default (to avoid accidental short-circuit). Refer to the schematic. You either have to close the pads left for the resistor (or place 0R resistor size 0603) or connect both MOD-IO and BME280 in parallel to the ESP32 board.
2. How do you power the MOD-IO? Is it via the power jack?
3. What exactly is the BME280 module and how do you connect it to the UEXT female connector?
2. How do you power the MOD-IO? Is it via the power jack?
3. What exactly is the BME280 module and how do you connect it to the UEXT female connector?
#8
ESP32 / Re: ESP32-P4 micropython port
Last post by LubOlimex - November 04, 2025, 08:17:59 AMThank you for this, I am sure someone will find it helpful!
#9
A20 / Re: [Source][PoC] U-Boot + Ker...
Last post by son.nguyenhong - November 04, 2025, 05:30:21 AMQuote from: LubOlimex on November 03, 2025, 08:26:56 AMThanks for this. So the NAND works? It is visible and you are capable to store data on it?NAND work as old day. But i dont recommend running OS on NAND for production task because data safety.
#10
UEXT / Re: ESP32-PoE-ISO-16MB --> MOD...
Last post by swaff - November 04, 2025, 03:05:19 AMI have tried plugging just the BME280 in and it works fine. As far as I can tell, it seems to be an issue with I2C communication.